Phytochemical Profiling and Dual Antioxidant/Anti-Inflammatory Activities of the Ethanolic Leaf Extract of Morinda lucida Benth: A Mechanistic in vitro Study

Abstract

Background: Morinda lucida Benth. is a West African medicinal plant used traditionally for conditions associated with oxidative stress and inflammation, but detailed evaluation of the phytochemical composition and in vitro anti-inflammatory mechanisms of its ethanolic leaf extract remains limited. Objective: This study evaluated the phytochemical profile, antioxidant capacity, and in vitro anti-inflammatory activity of the ethanolic leaf extract of M. lucida. Methods: Dried leaf powder was extracted by ethanol maceration. Qualitative and quantitative phytochemical analyses were performed, while antioxidant activity was assessed using DPPH radical scavenging, ferric reducing antioxidant power (FRAP), and hydrogen peroxide (H₂O₂) scavenging assays. Anti-inflammatory activity was evaluated using inhibition of heat-induced bovine serum albumin denaturation and human erythrocyte membrane stabilisation assays, with ascorbic acid and diclofenac sodium as reference standards. Results: The crude extract yield was 14.2% (w/w). Total phenolic and flavonoid contents were 92.64 ± 1.15 mg GAE/g and 48.36 ± 0.84 mg QE/g, respectively. The extract showed concentration-dependent antioxidant activity, with a DPPH IC₅₀ of 42.8 µg/mL, a FRAP value of 812 ± 15 µmol Fe²⁺/g, and 74.6% H₂O₂ scavenging at 100 µg/mL. It also inhibited protein denaturation (IC₅₀ = 121.5 µg/mL) and stabilised erythrocyte membranes (IC₅₀ = 103.2 µg/mL). Conclusion: The ethanolic leaf extract demonstrated measurable antioxidant and anti-inflammatory activities under the in vitro conditions employed, supporting further bioassay-guided fractionation and in vivo validation.